JavassistProxyFactory  其實用了代理的模式

SqlSessionFactoryBean 實現了InitializingBean接口,實力化的時候調用afterPropertiesSet，從而初始化sqlSessionFactory
其次定義MapperScannerConfigurer  實現了BeanDefinitionRegistryPostProcessor接口,會在實例化 前調用

ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
scanner.setAddToConfig(this.addToConfig);
scanner.setAnnotationClass(this.annotationClass);
scanner.setMarkerInterface(this.markerInterface);
scanner.setSqlSessionFactory(this.sqlSessionFactory);
scanner.setSqlSessionTemplate(this.sqlSessionTemplate);
scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);
scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);
scanner.setResourceLoader(this.applicationContext);
scanner.setBeanNameGenerator(this.nameGenerator);
scanner.setMapperFactoryBeanClass(this.mapperFactoryBeanClass);
if (StringUtils.hasText(this.lazyInitialization)) {
    scanner.setLazyInitialization(Boolean.valueOf(this.lazyInitialization));
}

scanner.registerFilters();
//會在這里掃描,
scanner.scan(StringUtils.tokenizeToStringArray(this.basePackage, ",; \t\n"));




->進入ClassPathMapperScanner的scan->doScan方法

public int scan(String... basePackages) {
    int beanCountAtScanStart = this.registry.getBeanDefinitionCount();
    this.doScan(basePackages);
    if (this.includeAnnotationConfig) {
        AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
    }

    return this.registry.getBeanDefinitionCount() - beanCountAtScanStart;
}

public Set<BeanDefinitionHolder> doScan(String... basePackages) {
     //封裝了beandefinition了
    Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
    if (beanDefinitions.isEmpty()) {
        LOGGER.warn(() -> {
            return "No MyBatis mapper was found in '" + Arrays.toString(basePackages) + "' package. Please check your configuration.";
        });
    } else {
　　　　//處理beanDefinitions

        this.processBeanDefinitions(beanDefinitions);
    }

    return beanDefinitions;
}


-> 

private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) {
    GenericBeanDefinition definition;
    for(Iterator var3 = beanDefinitions.iterator(); var3.hasNext(); definition.setLazyInit(this.lazyInitialization)) {
        BeanDefinitionHolder holder = (BeanDefinitionHolder)var3.next();
        definition = (GenericBeanDefinition)holder.getBeanDefinition();
        String beanClassName = definition.getBeanClassName();
        LOGGER.debug(() -> {
            return "Creating MapperFactoryBean with name '" + holder.getBeanName() + "' and '" + beanClassName + "' mapperInterface";
        });
        definition.getConstructorArgumentValues().addGenericArgumentValue(beanClassName);
　　　　　//設置了 private Class<? extends MapperFactoryBean> mapperFactoryBeanClass = MapperFactoryBean.class;，我們看看 MapperFactoryBean

        definition.setBeanClass(this.mapperFactoryBeanClass);
        definition.getPropertyValues().add("addToConfig", this.addToConfig);

。。。
}

->進入MapperFactoryBean的getObject

方法

public class MapperFactoryBean<T> extends SqlSessionDaoSupport implements FactoryBean<T> {
    private Class<T> mapperInterface;
    ...
　　繼承了SqlSessionDaoSupport

    public T getObject() throws Exception {
        return this.getSqlSession().getMapper(this.mapperInterface);
    }

public abstract class SqlSessionDaoSupport extends DaoSupport {
　　//組合了形式擁有session
    private SqlSessionTemplate sqlSessionTemplate;

    public SqlSessionDaoSupport() {
    }

    public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
        if (this.sqlSessionTemplate == null || sqlSessionFactory != this.sqlSessionTemplate.getSqlSessionFactory()) {
            this.sqlSessionTemplate = this.createSqlSessionTemplate(sqlSessionFactory);
        }

    }

    protected SqlSessionTemplate createSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

    public final SqlSessionFactory getSqlSessionFactory() {
        return this.sqlSessionTemplate != null ? this.sqlSessionTemplate.getSqlSessionFactory() : null;
    }

    public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
        this.sqlSessionTemplate = sqlSessionTemplate;
    }

    public SqlSession getSqlSession() {
        return this.sqlSessionTemplate;
    }

    public SqlSessionTemplate getSqlSessionTemplate() {
        return this.sqlSessionTemplate;
    }

    protected void checkDaoConfig() {
        Assert.notNull(this.sqlSessionTemplate, "Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required");
    }
}

public class SqlSessionTemplate implements SqlSession, DisposableBean {
    private final SqlSessionFactory sqlSessionFactory;
    private final ExecutorType executorType;
    private final SqlSession sqlSessionProxy;
    private final PersistenceExceptionTranslator exceptionTranslator;

    public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType());
    }

    public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType) {
        this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator(sqlSessionFactory.getConfiguration().getEnvironment().getDataSource(), true));
    }

    public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) {
        Assert.notNull(sqlSessionFactory, "Property 'sqlSessionFactory' is required");
        Assert.notNull(executorType, "Property 'executorType' is required");
        this.sqlSessionFactory = sqlSessionFactory;
        this.executorType = executorType;
        this.exceptionTranslator = exceptionTranslator;
        //
        this.sqlSessionProxy = (SqlSession)Proxy.newProxyInstance(SqlSessionFactory.class.getClassLoader(), new Class[]{SqlSession.class}, new SqlSessionInterceptor());
    }
。。。
}